dm: treewide: Rename 'platdata' variables to just 'plat'

We use 'priv' for private data but often use 'platdata' for platform data.
We can't really use 'pdata' since that is ambiguous (it could mean private
or platform data).

Rename some of the latter variables to end with 'plat' for consistency.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/cmd/Kconfig b/cmd/Kconfig
index c853ce7..da86a94 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -1917,7 +1917,7 @@
 
 	  The '-f' (force) option can be used for set the value which exceeds
 	  the limits, which are found in device-tree and are kept in regulator's
-	  uclass platdata structure.
+	  uclass plat structure.
 
 endmenu